Thought this may be of interest. I copied it from a plow site fourm
"A few weeks ago we took our 2002 duramax 3500 into the shop because it was clunking. I thought it was a U joint. The mechanic found the clunk quick. It was a loose transfer case. He said they see a lot of them come through loose, and if you don't catch it it makes a big mess. I figured this info might help a few here before any damage is done."
2002 d/a,c/c,s/b,white w/ blk flares,tech iv pcm programmer-duramaximiser,fipk,dynomax muffler on oem 3.5 inch exhaust,husky floor liners and mud flaps,vent visors,interco trxus 255/85/16,amsoil bumper to bumper.